Not Applicable
Not Applicable
Finger jointing machines are used to mill joints in the ends of random lengths of lumber, hereafter referred to as xe2x80x9cblocksxe2x80x9d. Glue is applied to the joints and the blocks are pressed together to form longer pieces of lumber. This is an oversimplification of a precise, complicated process known as finger jointing, but the focus of this invention is the accurate feeding of finger joint machines with blocks, not the process of finger jointing blocks.
This invention relates generally to an apparatus that requires no human operator and that accepts a random and haphazard delivery of blocks from a supply conveying means, ensures that every block has an acceptable moisture content and delivers a consistent, correctly aligned and correctly orientated supply of blocks at precise intervals to the finger joint machine""s lug or slat chain at any lineal speed that is determined by that finger joint machine.
This invention applies to finger joint machines which use either a chain with lugs spaced at regular intervals thereon or a plurality of chains connected by slats at regular intervals to push a block through the said machine""s shaper head or heads. The former type of finger joint machine is referred to as a lug chain finger joint machine and the latter is known as a slat chain finger joint machine. The phrase xe2x80x9clug chainxe2x80x9d includes the xe2x80x9cfinger joint lug chainxe2x80x9d and the xe2x80x9cfinger joint slat chainxe2x80x9d, but the phrase xe2x80x9cfinger joint slat chainxe2x80x9d may be used herein when necessary. Lugs or slats attached to the lug chain are referred to as xe2x80x9clugsxe2x80x9d herein, ignoring the difference between a lug and a slat. The means to supply either type of finger jointing machine with raw material is known as a lug loader by those knowledgeable in the art. Placing a block ahead of a lug is referred to as placing a block xe2x80x9con lugxe2x80x9d herein. For clarity, the longitudinal left hand end of any apparatus is defined herein as the infeed, where blocks are deposited to be eventually fed to the finger joint machine. The right hand end of the same apparatus is defined as the outfeed where blocks are deposited on the finger joint machine. The direction of travel is assumed herein to be from left to right and upstream refers toward the infeed and downstream refers toward the outfeed. The words xe2x80x9csprocketxe2x80x9d and xe2x80x9cchainxe2x80x9d may sometimes refer to a multiplicity of sprockets and/or chains, but the singular is generally used.
Historically, finger joint machines were supplied with blocks manually. FIG. 1 illustrates the steps required to place blocks on a lug chain manually. A supply means 1 deposits blocks 2 on an accumulation table 4, where a person 3 picks up a block 2, aligns and places it on the finger joint machine""s 6 lug chain 7. Human dexterity became incapable of placing a block in each lug 5 of the lug chain 7 as lug speed and operating speed increased. Empty lugs represent lost production, increased costs and less profit. Workers also suffer injuries while placing blocks manually on lug, thereby increasing production costs with production down time, employee sick leave, various forms of compensation, new operator training and rehabilitation of the injured worker.
Mechanical lug loaders were invented to supplement or replace manual lug loading and work with varying degrees of success. Some individuals, such as Hill, U.S. Pat. No. 6,189,682, U.S. Pat. No. 5,617,910, Cromeen, U.S. Pat. No. 4,429,784, U.S. Pat. No. 4,246,943, Hahn et al., U.S. Pat. No. 4,039,108, and others, were awarded patents for their inventions. Others put their inventions to work in their own manufacturing operations without patent protection.
Lug loaders have generally comprised four separate means to accomplish the task of placing blocks on lug: a supply means, a powered accumulation means, a control means and a powered transfer means.
FIG. 2 illustrates the steps required to load a finger joint machine""s lug chain 7 with blocks 2 using a prior art lug loader (sensors and electronic means required to control the prior art lug loader have not been shown).
A supply means 1, which may be a vibrating conveyor, belt conveyor, or some other means, deposits blocks 2 in a haphazard and random fashion on an accumulation means 9, where a person 3 manually picks up a block 2, orientates it in a side-by-side, parallel manner with other blocks 2 with its widest face down and one of its ends aligned to a fence 8, which represents a datum line that continues to the finger joint machine""s own fence. A fence 8 may be understood as an obstruction that runs longitudinally along one side of the accumulation means 9 from its infeed to its outfeed in a more or less straight line. Workers must ensure that blocks 2 always maintain contact with the fence 8 and that blocks 2 remain at right angles to the fence 8, because block ends may not be milled correctly by the finger joint machine 6, if they are placed on the lug chain 7 at some distance from the fence 8.
The block is then moved under the powered brush hold down 12 on the accumulation means 9 and is pushed in the direction of travel until it is stopped at the control means 10. The control means 10 releases blocks 2 onto the transfer means 11 at intervals synchronized with the lugs 5. Synchronization may be achieved by electrical or mechanical means and various means, such as levers or pinch rolls employing pressure cylinder means, are used to release blocks from the accumulation means 9 to the transfer means 11.
The transfer means 11, that bridges the gap between the accumulation means 10 and the lug chain 7, is often comprised of two features: a form of table that blocks lie on and an overhead conveying means. The table generally has a low coefficient of friction and may be comprised of sheet metal, skate wheels, or synthetic materials such as UHMW, which encourage the overhead conveying means 12 to push the block 2 across the transfer table 11 smoothly. The overhead conveying means 12, which may be comprised of a powered brush hold down or a powered, narrow polyethylene belt conveyor, applies pressure against the block 2 and pushes it across the transfer table 11. Overhead conveying means 12 usually require precise adjustment for block thickness to work satisfactorily, otherwise malfunctions may occur.
The transfer means 11, assisted by the powered brush hold down 12, deposits the blocks 2 on the lug chain 7.
Problems often occur when block lengths vary significantly, for example 5xc2xd xe2x80x3 to 55xe2x80x3, because the longer length blocks tend to push around the shorter blocks on the accumulation table and under the powered hold down. Problems also occur on the transfer table because one end of a block is controlled better than the other. In each case, this causes one end of the block to lag behind the other, which may cause the block to move away from the right angled orientation required by the finger joint machine. Various means, such as powered hold down brushes, have been developed to remedy this problem, with limited success, and manual intervention is usually required to ensure satisfactory block alignment for the control means.
A finger joint machine may tolerate some poor orientation and misalignment, but mismanufacture and/or damage may occur if blocks become seriously disturbed, especially if a block jams between the finger joint machine""s lugs.
Lug loading means do not normally include a means to determine block moisture content and a means to process those blocks with unacceptable moisture content. Block moisture content is critical to the glueing and glue curing process of finger joint lumber manufacturing, because incorrect block moisture content may cause glue line failure and the rejection of a manufacturing shift""s total production output.
The invention differs from prior art significantly and represents a complete finger joint machine infeed system. It does not require manual labor and does not use a conventional accumulation, control, or transfer means, but it can receive blocks in a haphazard and random fashion from a supply means, orientate and align the blocks accurately, reject blocks with unacceptable moisture content and deposit blocks at precise and controlled intervals on the lug chain, regardless of block length variance, and at any lineal speed that the lug chain may run at.
Various means have been invented to supply finger joint machines with an automatic, continuous supply of random length blocks. Hill, U.S. Pat. Nos. 6,189,682 and 5,617,910, Cromeens, U.S. Pat. Nos. 4,429,784 and 3,927,705, and Hahn et al., U.S. Pat. No. 4,039,108, each describe a method to feed blocks to finger joint machines and these means are known to persons knowledgeable in the art.
This invention is a novel and ingenious departure from the prior art and comprises an unmanned, automatic finger joint machine infeed means, complete with a means to receive random length blocks from a supply means; a means to orientate, singularize and align the blocks, a means to detect the moisture content of each block and reject that block if necessary, and a means to dispense blocks to the lug chain at precisely defined intervals. The invention will operate throughout the lug chain""s lineal speed range, specifically full stop to full speed, without adjustment or interruption and performs this continuously, automatically and accurately and does not require manual labor.
The invention will process variable width, thickness and length blocks, but blocks of similar width and thickness should be processed together. The preferred embodiment of the invention is one that will process blocks ranging in width from 2xc2xdxe2x80x3 to 7xc2xcxe2x80x3, thickness ranging from ⅝xe2x80x3 to 2xc2xcxe2x80x3 and lengths ranging from 5xc2xdxe2x80x3 to 55xe2x80x3, although the invention may process additional block dimensions.
The invention is comprised of six interdependent areas: the infeed conveyor, the unscrambler, the even ending conveyor, the excess block drop out gap, the moisture sensing area and the outfeed plate. A novel slat chain links all, but the infeed conveyor, together.
The infeed conveyor is furnished with blocks in a random and haphazard fashion by a supply conveying means and then deposits these blocks in the unscrambler. The preferred embodiment of this invention includes an infeed conveyor, but this may be omitted if required, as described below, in which case the supply conveyor deposits blocks directly into the unscrambler. The supply conveyor is not the preferred method of feeding the unscrambler with blocks, because this causes more severe block tumbling and churning within the unscrambler.
The slat chain moves upward through the unscrambler and its slats pick up individual blocks which are partially singularized and orientated at right angles to the direction of travel within the unscrambler. The slats push blocks across the even ending conveyor, which moves blocks transversely to contact the inside edge of one of the slat chains. This particular side of the slat chain is aligned with the finger joint machine""s fence, thereby ensuring that block ends are longitudinally aligned to the finger joint machine""s fence.
Blocks are then pushed across a short, flat table by the slats and under a block hold, which prevents the unsecured end of the block from dipping. If a block is not pinched by the hold down, it drops through a gap in the table and is returned to the supply conveying means by other conveying means. The slats then push blocks across a moisture detecting means. Any blocks with unacceptable moisture fall through a gap, which is created when the moisture detecting means causes a door to open, onto a conveying means which removes them to another area. Blocks with acceptable moisture are pushed across the said door onto an outfeed plate.
The preferred embodiment of this invention includes a block moisture detecting means, a gap through which blocks with unacceptable moisture content fall, a door to cover the said gap and a control means to operate the said door. However, the moisture detecting means and its associated elements may be omitted.
Contrary to other lug loaders and unscramblers, whose conveying means move downward to loop back to the infeed, the slats push blocks across the outfeed plate and then move upward away from the outfeed plate to eventually loop back under the infeed conveyor, if it is present, to the unscrambler, thereby allowing a flat, unbroken outfeed table that lies just above the lug chain. This ensures that slats deposits blocks at the end of the outfeed table in the same, precise location.
Blocks maintain continuous contact along their length with the slats and one end always contacts the slat chain. This eliminates all the problems caused by block lengths encountered by other lug loaders. The slat chain controls each block, from the unscrambler to the finger joint machine, and prevents incorrectly aligned blocks, thereby ensuring correct lateral alignment to the finger joint machine.
The slats are synchronized to the lugs, therefore every block, regardless of its width or length, is always deposited on the lug chain in the same orientation, alignment and precise location and at any lineal speed determined by the lug chain.
In summary, the invention accepts a random and haphazard delivery of blocks from a supply conveyor, ensures that every block has an acceptable moisture content and delivers a consistent, correctly aligned and correctly orientated supply of blocks at precise intervals to the lug chain at any speed determined by the finger joint machine. This is performed automatically without human intervention.